---
title: "How to Validate Data?"
description: "Validation on record save, during import, and via field rules in the table editor."
---

# How to Validate Data?

Custom Data v2 has no separate **Validate entire table** button. Checks happen **when you save** records, **during import** (**Preview before import**), and through **field rules** set in the table editor.

## When Needed

- You need to ensure new rows follow rules (email, required, unique).
- You import a file and want errors before rows are written.
- Operators fill record forms — the system should flag invalid values.

## What's Important to Know

- **Field rules** — on the editor **Fields** tab: **Required**, **email**, **url**, **digits**, **json**, etc.
- **Save-time validation** — inline in the table or record card; invalid values are not saved and show a hint.
- **Import** — **Preview before import** lists **Invalid rows**; critical errors block import until mapping or the file is fixed.
- Complex cross-field rules (e.g. end time after start time) need advanced setup — see an integrator or the [advanced options reference](/en/customdata/reference/advanced-model-options-reference.md).

## Prerequisites

- [x] You opened **Menu → Custom Data**.
- [x] Field rules are configured or you are preparing an import.

## Validate while editing records

1. Open the table from **Tables**.
2. Add or edit a row (inline or **Add row** / record card).
3. Fill fields with rules (required, email, etc.).
4. Try **Save** — invalid values highlight and do not persist.
5. Fix values and save again.

## Validate before import

1. Start **Import data** ([guide](/en/customdata/how-to/import-data-from-file.md)).
2. Proceed to **Preview before import**.
3. Review the preview table and **Invalid rows**.
4. Fix mapping, field types, or the file — repeat preview until critical errors are gone.
5. Confirm import.

## Configure rules in table structure

1. **Edit** the table → **Fields** tab.
2. Add or open a field → in the field card:
   - enable **Required**;
   - pick a semantic type with built-in checks (email, url);
   - add **Validation rules** if needed.
3. **Save** the structure.

## How to Verify

- Invalid email or empty required fields do not save.
- Import with bad rows shows them on preview and blocks completion when critical.
- After rule changes, new records use updated checks.

## Related Materials

- [Import data from file](/en/customdata/how-to/import-data-from-file.md)
- [Configure field type](/en/customdata/how-to/configure-field-type.md)
- [Advanced model options reference](/en/customdata/reference/advanced-model-options-reference.md)